Darwowned is a conflation of the slang phrase "owned" or its Internet variant "pwned" and "Darwin", the name of the author of a theory of evolution and familiar in pop culture from "the Darwin Awards", anecdotal tales of individuals who have, through lack of foresight or intelligence, killed themselves and thus will not contribute personally to the species' gene pool.
Thus, to be "Darwowned" is to "owned" by a situation or event directly related to one's faulty sense of self-preservation.
Dude loved that camera so much he went onto the tracks to get a better picture, but he was Darwowned by the train.
"Darwowned!" shouted the crowd as the one-legged tightrope walker plummeted to the concrete.